Method of supporting a substrate film

ABSTRACT

The invention relates to a carrier for supporting a substrate film during the chip-substrate assembly and bonding process. The carrier provides enhanced rigidity to the substrate film. The degree of rigidity and/or flexibility provided can be controlled by selection of the carrier dimensions, configuration and material choice. Advantages of embodiments of the carrier include easier handling, reduced probability of defective end products, and increased control in choosing the thinness of the substrate film. For example, the substrate film carrier can be used for lead-over-chip (LOC) assemblies and lead-under-chip (LUC) assemblies to create ball grid arrays (BGA), pin grid arrays (PGA), dual in-line packages (DIP), and the like.

RELATED APPLICATION

[0001] This application is a continuation of U.S. application Ser. No.09/858,118, filed May 15, 2001, which is a divisional of U.S.application Ser. No. 09/389,720, filed Sep. 3, 1999, the entirety ofeach one of which is hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to the handling ofsemiconductor chips and, specifically, to a carrier adapted forsupporting a substrate film during the assembly and bonding process.

[0004] 2. Background

[0005] In today's integrated circuit (IC) technology, semiconductorchips or dies are typically batch fabricated on a silicon wafer. Thewafer may contain hundreds of dies arranged in a matrix. The dies areseparated and each die is typically mounted on an appropriate substrate,contacted, and packaged.

[0006] The substrate is typically a thin flexible tape or film reelwhich permits automated transport and handling of the dies. Many diesmay be attached adjacently to a single tape using, for example, asuitable adhesive material. Bond pads on the dies and the substrate filmallow the dies to be wire bonded or connected, using suitable leads, tothe substrate. The die-substrate assemblies may then be cut intoindividual units. Each unit is packaged in a suitable medium with outputleads, for example, ball grid arrays (BGA), pin grid arrays (PGA), dualin-line packages (DIP), and the like. The outputs of these packagesallow interconnections to a similarly patterned arrangement ofconnections on a printed circuit board (PCB).

[0007] The thinness of the substrate film or tape is advantageous inthat it does not significantly add to the weight and size of the endproduct. But this thinness can also cause the substrate film reel to befragile and flimsy. As a result, during the assembly process, the filmis prone to undesirable and/or unwanted bending and movement. Thiscannot only cause damage to the die, the substrate and the die-substrateinterface, but can also complicate the handling and assembly of the dieand substrate. For example, undesirable bending of the film substratecan result in breakage of one or more of the leads connecting the diesto the substrate.

SUMMARY OF THE INVENTION

[0008] The invention relates to a carrier for supporting a substratefilm during the chip-substrate assembly and bonding process. The carrierprovides enhanced rigidity to the substrate film. The degree of rigidityand/or flexibility provided can be controlled by selection of thecarrier dimensions, configuration and material choice. Advantages ofembodiments of the carrier include easier handling, reduced probabilityof defective end products, and increased control in choosing thethinness of the substrate film. For example, the substrate film carriercan be used for lead-over-chip (LOC) assemblies and lead-under-chip(LUC) assemblies to create ball grid arrays (BGA), pin grid arrays(PGA), dual in-line packages (DIP), and the like.

[0009] In one embodiment, a carrier for supporting a substrate filmcomprises side bars and cross bars. The side bars and cross bars are inmechanical communication with the substrate film and provide rigidityduring the manufacturing process. In another embodiment, an assemblycomprises a substrate film and a carrier. The carrier comprises sidebars which are in mechanical communication with the substrate film.

[0010] In another embodiment, an assembly comprises a film and acarrier. The film includes a plurality of substrate units. The pluralityof substrate units is adapted to electrically interface with a pluralityof dies. The carrier is in mechanical communication with the film. Thecarrier provides enhanced rigidity to the film by being sized andconfigured to add material at selected regions of the film.

[0011] In another embodiment, an assembly for attachment of integratedcircuits comprises a film, a plurality of dies and a carrier. The filmincludes a plurality of substrate units. The plurality of dies are inelectrical contact with the plurality of substrate units. The carrier isin mechanical communication with the film for providing enhancedrigidity to the film.

[0012] One embodiment of the invention relates to method for supportinga substrate film. The method comprises connecting side bars to asubstrate film and connecting cross bars to the substrate film, wherebythe side bars and the cross bars provide rigidity during themanufacturing process.

[0013] Another embodiment relates to a method of manufacturing anassembly. The method comprises connecting side bars to a substrate filmand transporting the side bars and the substrate film through amanufacturing process. The method further comprises removing the sidebars after at least a portion of the manufacturing process.

[0014] An additional embodiment relates to a method of processingsemiconductor dies. The method comprises forming a plurality ofsubstrate units within a film and interfacing the substrate units with aplurality of dies. The method further comprises adding support materialat selected regions of the film so as to provide enhanced rigidity tothe substrate units. The method also comprises removing the supportmaterial at the completion of at least a portion of a manufacturingprocess.

[0015] One embodiment relates to a method of manufacturing integratedcircuits. The method comprises forming a plurality of substrate unitswithin a substrate film and interfacing a plurality of dies to theplurality of substrate units. The method further comprises connecting acarrier to the film to enhance the rigidity of the film.

[0016] For purposes of summarizing the invention, certain aspects,advantages and novel features of the invention have been describedherein above. Of course, it is to be understood that not necessarily allsuch advantages may be achieved in accordance with any particularembodiment of the invention. Thus, the invention may be embodied orcarried out in a manner that achieves or optimizes one advantage orgroup of advantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein.

[0017] All of these embodiments are intended to be within the scope ofthe invention herein disclosed. These and other embodiments of thepresent invention will become readily apparent to those skilled in theart from the following detailed description of the preferred embodimentshaving reference to the attached figures, the invention not beinglimited to any particular preferred embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a schematic exploded perspective view of one embodimentof a ball grid array (BGA) chip package and a printed circuit board(PCB);

[0019]FIG. 2 is a partially exploded perspective view of a substratefilm, carrier and lead-over-chip (LOC) die assembly in accordance withone embodiment of the present invention;

[0020]FIG. 3 is a top plan view of the substrate film of FIG. 2;

[0021]FIG. 4 is a top plan view of the substrate film and carrier ofFIG. 2;

[0022]FIG. 5 is a schematic cross-sectional view along line 5-5 of FIG.4 in accordance with one embodiment of the present invention;

[0023]FIG. 6 is a schematic cross-sectional view along line 5-5 of FIG.4 in accordance with another embodiment of the present invention; and

[0024]FIG. 7 is a schematic cross-sectional view along line 5-5 of FIG.4 in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025]FIG. 1 schematically illustrates a ball grid array (BGA) chippackage 10 and a printed circuit board (PCB) 12. The BGA package 10serves as an encapsulating device for a die or chip and permitselectrical access to the die via solder or electrode bumps 14. The PCB12 includes a pattern of pads 16 which are arranged in alignment withthe BGA solder bumps 14. This allows the BGA chip package 10 to beconnected to the PCB 12. Of course, other chip packaging types may alsobe used, for example, pin grid arrays (PGA), dual in-line packages(DIP), and the like. These packaging types can be connected tocompatible connectors on a PCB or other external circuitry.

[0026] In accordance with one embodiment, FIG. 2 is a representation ofa lead-over-chip (LOC) assembly 17 and generally shows a substrate film18, a film carrier or structure 20 and a semiconductor die or chip 22.The substrate film 18 includes a plurality of substrate units 24, asdiscussed in greater detail below, with each unit 24 being interfaceablewith an individual die 22. The die 22 includes a plurality of bondingpads 28 which are in electrical contact with the integrated circuitsformed on the die 22. During assembly, the die 22 is adhered to thesubstrate unit 24 and the bonding pads 28 are electrically contacted totraces 26 formed on or in the substrate unit 24 through die lead wires(not shown). In turn, the LOC die-substrate assembly 17 is separatedfrom the substrate film 18 and packaged, for example, in the BGA chippackage 10 (FIG. 1) with the substrate electrical traces 26 inelectrical contact with the solder bumps 14 (FIG. 1). This permits thedie 22 to be electrically interfaced with external circuitry, forexample, the PCB 12 (FIG. 1). The LOC die-substrate assembly 17 can alsobe packaged in other forms, for example and as indicated above, usingpin grid arrays (PGA), dual in-line packages (DIP), and the like.

[0027] In general, the substrate film carrier 20 (FIG. 2) may be used inconnection with various types of die-substrate assemblies to providerigidity to the substrate film 18 (FIG. 2) during handling. In oneembodiment, the substrate film carrier 20 is used in conjunction with alead-under-chip (LUC). The structure of such LUC assemblies is wellknown in the art, and hence will not be discussed in detail herein.

[0028] The die attach materials and equipment are commercially availablefrom suppliers such as Dow Corning, Hitachi and ShinEtsu, among others.The lead bond tools and equipment are commercially available fromsuppliers such as Gaiser, Hitachi, Shinkawa and others. Theencapsulation materials and equipment are commercially available fromsuppliers such as Ablestick, Asymtek, Dow Corning, Hitachi, 3M, ShinEtsuand others.

[0029]FIG. 3 shows a substrate film or tape 18 in accordance with oneembodiment. The substrate film 18 generally includes a plurality ofsubstrate units or elements 24, and side rails 30 and 32 which areinterconnected by end rails 34 and 36 and a plurality of cross rails 38.The side rails 30, 32 have a plurality of indexing holes 40 thatfacilitate transport and indexing of the substrate film 18, for example,during automated assembling. In one embodiment, as shown in FIG. 3, theside rails 30, 32 also include projecting portions 33 which define twoof the edges of the substrate units 24.

[0030] In one embodiment, the substrate film 18 (FIG. 3) includeseighteen substrate units 24 grouped in substrate sets 42 with eachsubstrate set 42 including three substrate units 24. The cross rails 38serve to space adjacent substrate sets 42. Those skilled in the art willreadily recognize that the number of substrate units 24 in the substratefilm 18 and the number of substrate units 24 forming each substrate set42 can be increased or decreased with efficacy, as required or desired.

[0031] Referring to FIG. 3, each substrate unit 24 is flanked by a pairof spacing and/or separating slots 44. The substrate unit 24 includes aplurality of electrical traces 26 with bond pads 50 formed thereon, anda generally central cavity 46 adjacent to a pair of adhesive tabs 48formed on the under-surface of the substrate film 18.

[0032] As indicated above, and with reference to FIGS. 2 and 3, theadhesive tabs 48 permit a plurality of dies, for example, the die 22, tobe adhered to respective substrate units 24. The substrate unit cavity46 is configured so that when the die 22 is in attachment with thesubstrate unit 24 the die bonding pads 28 are exposed. This allows dielead wires (not shown) to pass through the cavity 46 and be wire bondedto the die bonding pads 28 and corresponding substrate bond pads 50. Inturn, other bond pads 50 in electrical contact with the electricaltraces 26 permit the substrate unit 24, and hence the die 22, to beexternally interfaced, for example, via the solder or electrode bumps 14(FIG. 1).

[0033] The substrate bond pads 50 (FIGS. 2 and 3) can be connected tothe solder bumps 14 (FIG. 1) in a number of ways as is known in the art,for example, by utilizing an interposer element within the chippackaging. In one embodiment, each substrate unit 24 also includesalignment holes 52 which facilitate alignment of the die-substrateassembly, for example, the LOC assembly 17 during encapsulation.

[0034] In one embodiment, the substrate film 18 (FIG. 3) is fabricatedfrom polyimide. Such substrate films 18 are commercially available froma wide variety of sources, for example, 3M, Casio, Shinko, Rite Flex andothers. Typically, the fabrication of the film or tape 18 begins withproviding a polyimide tape which is sandwiched on either side by a layerof copper and an outer layer of solder resist/mask. The desiredelectrical “artwork” is then etched on the polyimide tape. The skilledartisan will understand, however, that a variety of other non-conductivematerials and processes can be used to create the substrate film 18.

[0035] Referring to FIGS. 2 and 3, the wire bonding of the die leadwires (not shown) to the die bonding pads 28 and substrate bond pads 50can utilize one of several methods known in the art. For example,thermal compression bonding, ultrasonic bonding, and pulse bonding maybe used. The die lead wires are typically made out of either gold oraluminum, but other materials may be used, as required or desired,giving due consideration to the goal of providing reliable electricalcontacts. The substrate bond pads 50 are fabricated from gold platedcopper, though a variety of other materials can be used, as required ordesired, giving due consideration to the goal of providing reliableelectrical contacts.

[0036] Referring to FIG. 3, in one embodiment, the substrate film 18 hasa thickness in the range from about 0.125 mm to 0.120 mm, a length inthe range from about 182.03 mm to 182.93 mm and a width in the rangefrom about 27.13 mm to 27.23 mm. However, in other embodiments, theskilled artisan will recognize that the substrate film 18 may be adaptedto have a wide variety of other thicknesses, lengths and widths.

[0037] The side rails 30, 32 have a thickness in the range from about0.125 mm to 0.120 mm, a length in the range from about 182.03 mm to182.93 mm, and a width in the range from 27.13 mm to 27.23 mm. The siderail projecting portions 33 extend inwards about 4.32 mm and are about6.63 wide. However, in other embodiments, the skilled artisan willrecognize that the side rails 30, 32 may be adapted to have a widevariety of other dimensions.

[0038] The end rails 34, 36 have a thickness in the range from about0.125 mm to 0.120 mm, a length in the range from about 27.13 mm to 27.23mm, and a width in the range from about 1.03 mm to 1.11 mm. However, inother embodiments, the skilled artisan will recognize that the end rails34, 36 may be adapted to have a wide variety of other dimensions.

[0039] The cross rails 38 have a thickness in the range from about 0.125mm to 0.120 mm, a length in the range from about 27.13 mm to 27.23 mm,and a width in the range from about 2.11 mm to 2.21 mm. In oneembodiment, the spacing between neighboring cross rails 38 is in therange from about 5.03 mm to 5.11 mm. However, in other embodiments, theskilled artisan will recognize that the cross rails 38 may be adapted tohave a wide variety of other dimensions and spacings. In one embodiment,the substrate film 18 includes five cross rails 38. However, in otherembodiments, the substrate film 18 may include fewer or more cross rails38.

[0040] The slots 44 have a length in the range from about 18.49 mm to18.59 mm and a width in the range from about 2.11 mm to 2.21 mm. In oneembodiment, the spacing between neighboring slots 44 is in the rangefrom about 5.03 mm to 5.11 mm. However, in other embodiments, theskilled artisan will recognize that the slots 44 may be adapted to havea wide variety of other dimensions and spacings. In one embodiment, thesubstrate film 18 includes seventeen slots 44. However, in otherembodiments, the substrate film 18 may include fewer or more slots 44.

[0041] The cavities 46 have a length in the range from about 15.95 mm to16.05 mm and a width in the range from about 7.95 mm to 8.05 mm. In oneembodiment, the spacing between neighboring cavities 46 is in the rangefrom about 10.11 mm to 10.21 mm. However, in other embodiments, theskilled artisan will recognize that the cavities 46 may be adapted tohave a wide variety of other dimensions and spacings. In one embodiment,the substrate film 18 includes eighteen cavities 46. However, in otherembodiments, the substrate film 18 may include fewer or more cavities46.

[0042] The substrate units 24 have a thickness in the range from about0.125 mm to 0.120 mm, a length in the range from about 182.03 mm to182.93 mm, and a width in the range from about 27.13 mm to 27.23 mm.However, in other embodiments, the skilled artisan will recognize thatthe substrate units 24 may be adapted to have a wide variety of otherdimensions. In one embodiment, the substrate film 18 includes eighteensubstrate units 24. However, in other embodiments, the substrate film 18may include fewer or more substrate units 24.

[0043] In one embodiment, the substrate film 18 includes six substratesets 42. Each of the substrate sets 42 includes three substrate units24. However, in other embodiments, the skilled artisan will realize thatthe substrate film 18 may include fewer or more substrate sets 42 andeach substrate set 42 may include fewer or more substrate units 24.

[0044] The indexing holes 40 have a diameter in the range from about1.574 mm to 1.499 mm. However, in other embodiments, the skilled artisanwill recognize that the indexing holes 40 may be adapted to have a widevariety of other diameters. In one embodiment, each substrate unit 24 isassociated with three indexing holes 40. However, in other embodiments,each substrate unit 24 may be associated with fewer or more indexingholes 40.

[0045]FIG. 4 shows the substrate film 18 supported by a carrier orstructure 20 in accordance with one embodiment to form a carrier-filmassembly 21. The substrate film carrier 20 provides increased rigidityfor the substrate film 18 which facilitates handling and assemblingprocesses. The carrier 20 generally includes side bars 60 and 62 whichare interconnected by end bars 64 and 66 and a plurality of cross bars68. The carrier side bars 60, 62 are substantially aligned with the filmside rails 30, 32 (FIG. 3) and include teeth 63 to form notches 65.

[0046] The teeth 63 are substantially aligned with the side railprojecting portions 33 and the notches 65 are substantially aligned withthe ends of the film slots 44. The carrier side bars 60, 62 also includeindexing holes 70 which are substantially aligned with the film indexingholes 40. Similarly, the carrier end bars 64, 66 are substantiallyaligned with the film end rails 34, 36 and the carrier cross bars 68 aresubstantially aligned with the film cross rails 38.

[0047] Referring to FIGS. 3 and 4, the substrate film carrier 20provides enhanced rigidity to the substrate film 18 by adding extramaterial on the film side rails 30, 32, film end rails 34, 36, and filmcross rails 38. In one embodiment, this is achieved by providing abalance between flexibility and rigidity. The carrier-film assembly 21is flexible enough so that it is easily handled by the processingmachines but it is also rigid enough to provide sufficient support forthe substrate film 18 during handling.

[0048] In one embodiment, and referring to FIG. 4, the carrier side bars60, 62, carrier end bars 64, 66, and carrier cross bars 68 aredimensioned to have substantially the same thickness. In otherembodiments, the carrier side bars 60, 62, carrier end bars 64, 66, andcarrier cross bars 68 can have different thicknesses.

[0049] In one embodiment, the substrate film carrier 20 comprises onlythe side bars 60, 62. In another embodiment, the substrate film carrier20 comprises only the cross bars 68. In yet another embodiment, thesubstrate film carrier 20 comprises the side bars 60, 62, and the crossbars 68. In a further embodiment, the substrate film carrier 20comprises the side bars 60, 62, and the end bars 64, 66. In yet anotherfurther embodiment, the substrate film carrier 20 comprises the end bars64, 66, and the cross bars 68.

[0050] Those skilled in the art will realize that the substrate filmcarrier 20 can be configured in many other ways, for example, andreferring to FIG. 4, the teeth 63 or notches 65 shown on the carrierside bars 60, 62 can be removed. Also, the substrate film carrier 20 canbe provided on the adhesive tab 48 side of the film 18 or on both sidesof the film 18, giving due consideration to the goal of providingenhanced rigidity. The substrate film carrier 20 may also extend beyondthe periphery and/or any edges of the film 18, as required or desired.Moreover, the film carrier can be constructed to adapt to the particularshapes and/or sizes of a wide range of substrate films, giving dueconsideration to the goals of providing length-wise and/or cross-wisesupport.

[0051] In one embodiment, as shown in FIG. 5, the substrate film carrier20 comprises a frame that is adhered to the substrate film 18 to formthe carrier-film assembly 21. The carrier/frame 20 may be attached tothe film 18 utilizing a wide variety of commercially available adhesivematerials. In one embodiment the adhesive material is selected such thatit can withstand a temperature of at least about 150 EC, for example,KAPTON, manufactured by 3M.

[0052] In one embodiment, the frame 20 is fabricated from BT resin. Theskilled artisan will understand, however, that a variety of materialscan be used for the substrate film carrier/frame 20 with efficacy,giving due consideration to the goal of providing enhanced rigidity forthe substrate film 18 (FIG. 3). The frame 20 (FIG. 5), in oneembodiment, can be manufactured by stamping a sheet of material in thedesired shape and then punching the indexing holes 70 in suitablepositions. However, the frame 20 may also be fabricated by other knownmanufacturing techniques.

[0053] In one embodiment, and referring to FIGS. 3, 4 and 5, the processof providing a packaged die, for example the BGA die package 10 (FIG.1), generally begins with the fabrication of the substrate film 18. Siderails 30, 32, end rails 34, 36, cross rails 38, indexing holes 40, slots44, cavities 46 and alignment holes 52 are created. The electrical“artwork” (electrical traces 26, bond pads 50) is formed on the film 18,in one embodiment, by an etching process. Adhesive tabs 48 are added tothe film 18.

[0054] In one embodiment, and referring to FIGS. 4 and 5, a substratefilm carrier/frame 20 is then formed. In one embodiment, the substratefilm carrier/frame 20 is manufactured by stamping a sheet of material toprovide side bars 60, 62, end bars 64, 66, and cross bars 68. Theindexing holes 70 are punched into the carrier 20. The carrier/frame 20is adhered to the film 18 and adds thickness to the film 18 at selectedlocations.

[0055] In one embodiment, and referring to FIGS. 4 and 5, dies 22 (FIG.2) are adhered to respective substrate units 24 utilizing the adhesivetabs 48. The dies 22 are wire bonded to the electrical traces 26 onrespective substrate units 24 to form a plurality of die-substrateassemblies, for example, the LOC assemblies 17 (FIG. 2). Thedie-substrate assemblies 17 are removed from the substrate film 18, forexample, by cutting. The die-substrate assemblies 17 are then packagedand tested to provide, for example, the BGA die package 10 (FIG. 1).

[0056] In one embodiment, the substrate film carrier 20 has a thicknessin the range from about 0.295 mm to 0.305 mm, a length in the range fromabout 182.03 mm to 182.93 mm and a width in the range from about 27.13mm to 27.23 mm. However, in other embodiments, the skilled artisan willrecognize that the substrate film carrier 20 may be adapted to have awide variety of other thicknesses, lengths and widths.

[0057] The side bars 60, 62 have a thickness in the range from about0.295 mm to 0.305 mm, a length in the range from about 182.03 mm to182.93 mm, and a width in the range from about 3.22 mm to 3.32 mm. Theside bar teeth 63 extend inwards about 1.07 mm and are about 7.95 mmwide. However, in other embodiments, the skilled artisan will recognizethat the side bars 60, 62 may be adapted to have a wide variety of otherdimensions.

[0058] The end bars 64, 66 have a thickness in the range from about0.295 mm to 0.305 mm, a length in the range from about 27.13 mm to 27.23mm, and a width in the range from about 1.03 mm to 1.11 mm. However, inother embodiments, the skilled artisan will recognize that the end bars64, 66 may be adapted to have a wide variety of other dimensions.

[0059] The cross bars 68 have a thickness in the range from about 0.295mm to 0.305 mm, a length in the range from about 27.13 mm to 27.23 mm,and a width in the range from about 2.11 mm to 2.21 mm. In oneembodiment, the spacing between neighboring cross bars 68 is in therange from about 5.03 mm to 5.11 mm. However, in other embodiments, theskilled artisan will recognize that the cross bars 68 may be adapted tohave a wide variety of other dimensions and spacings. In one embodiment,the substrate film carrier 20 includes five cross bars 68. However, inother embodiments, the substrate film carrier 20 may include fewer ormore cross bars 68.

[0060] The carrier indexing holes 70 have a diameter in the range fromabout 1.574 mm to 1.499 mm. However, in other embodiments, the skilledartisan will recognize that the indexing holes 70 may be adapted to havea wide variety of other diameters. In one embodiment, the carrier 20includes fifty-four indexing holes 70. However, in other embodiments,the substrate film carrier 20 may include fewer or more indexing holes70.

[0061] In another embodiment, as shown in FIG. 6, the substrate filmcarrier 20 is formed with the substrate film 18 to create thecarrier-film assembly 21. In one embodiment, the carrier 20 and the film18 are fabricated from polyimide. The skilled artisan will understand,however, that a variety of materials can be used for the carrier 20 andthe film 18. Referring to FIG. 6, the carrier 20 and the film 18 may bemanufactured by using known techniques, such as molding.

[0062] In one embodiment, and referring to FIGS. 3, 4 and 6, the processof providing a packaged die, for example the BGA die package 10 (FIG.1), generally begins with the fabrication of the substrate film 18 andthe carrier 20. Side rails 30, 32, end rails 34, 36, cross rails 38,indexing holes 40, slots 44, cavities 46 and alignment holes 52 arecreated. Side bars 60, 62, end bars 64, 66, cross bars 68, and indexingholes 70 are created. In one embodiment, a molding process is utilizedto form the carrier 20 with the film 18. The carrier 20 adds thicknessto the film 18 at selected locations.

[0063] Referring to FIGS. 3, 4 and 6, in one embodiment, the electrical“artwork” (electrical traces 26, bond pads 50) is formed on the film 18.In one embodiment this “artwork” is formed by an etching process.Adhesive tabs 48 are added to the film 18.

[0064] In one embodiment, and referring to FIGS. 4 and 6, dies 22 (FIG.2) are adhered to respective substrate units 24 utilizing the adhesivetabs 48. The dies 22 are wire bonded to the electrical traces 26 onrespective substrate units 24 to form a plurality of die-substrateassemblies, for example, the LOC assemblies 17. The die-substrateassemblies 17 are removed from the substrate film 18, for example, bycutting. The die-substrate assemblies 17 are then packaged and tested toprovide, for example, the BGA die package 10 (FIG. 1).

[0065] In one embodiment, the carrier 20 includes fifty-four indexingholes 70. However, in other embodiments, the substrate film carrier 20may include fewer or more indexing holes 70.

[0066] In another embodiment, as shown in FIG. 7, the substrate filmcarrier 20 comprises a plurality of layers 74 of material. In oneembodiment, the layers 74 are polyimide. In other embodiments, one ormore of the layers 74 are metallic, for example, copper, and/or soldermask. These latter embodiments may be desirable especially in thesituation, as indicated above, in which fabrication of the electrical“artwork” on the substrate film 18 utilizes layers of copper and solderresist.

[0067] For example, one or more layers 74 can be polyimide, one or morelayers 74 can be copper, and one or more layers 74 can be solder mask.The thickness of each layer 74 can be controlled, as required ordesired. Those skilled in the art will recognize that a number ofmaterials may be used to fabricate the layered carrier 20 shown in FIG.7.

[0068] For example, one or more layers 74 of material is provided toform side bars 60, 62, end bars 64, 66, and cross bars 68. The indexingholes 70 are punched into the carrier 20. As indicated above, the layers74 may also be formed during the fabrication of the film 18 and cancomprise copper and/or solder resist. The carrier 20 adds thickness tothe film 18 at selected locations.

[0069] The substrate film carrier 20 has a thickness in the range fromabout 0.125 mm to 0.120 mm, a length in the range from about 182.03 mmto 182.93 mm and a width in the range from about 27.13 mm to 27.23 mm.However, in other embodiments, the skilled artisan will recognize thatthe substrate film carrier 20 may be adapted to have a wide variety ofother thicknesses, lengths and widths.

[0070] The layers 74 may have a thickness in the range from about 0.125mm to 0.120 mm However, in other embodiments, the skilled artisan willrecognize that the layers 74 may be adapted to have a wide variety ofother thicknesses.

[0071] The side bars 60, 62 have a thickness in the range from about0.125 mm to .120 mm, a length in the range from about 182.03 mm to182.93 mm, and a width in the range from about 27.13 mm to 27.23 mm. Theside bar teeth 63 extend inwards about 4.32 mm and are about 6.63 mmwide. However, in other embodiments, the skilled artisan will recognizethat the side bars 60, 62 may be adapted to have a wide variety of otherdimensions.

[0072] The end bars 64, 66 have a thickness in the range from about0.125 mm to 0.120 mm, a length in the range from about 27.13 mm to 27.23mm, and a width in the range from about 1.03 mm to 1.11 mm. However, inother embodiments, the skilled artisan will recognize that the end bars64, 66 may be adapted to have a wide variety of other dimensions.

[0073] The cross bars 68 have a thickness in the range from about 0.125mm to 0.120 mm, a length in the range from about 27.13 mm to 27.23 mm,and a width in the range from about 2.11 mm to 2.21 mm. In oneembodiment, the spacing between neighboring cross bars 68 is in therange from about 5.03 mm to 5.11 mm. However, in other embodiments, theskilled artisan will recognize that the cross bars 68 may be adapted tohave a wide variety of other dimensions and spacings. In one embodiment,the substrate film carrier 20 includes five cross bars 68. However, inother embodiments, the substrate film carrier 20 may include fewer ormore cross bars 68.

[0074] The carrier indexing holes 70 have a diameter in the range fromabout 1.574 mm to 1.499 mm. However, in other embodiments, the skilledartisan will recognize that the indexing holes 70 may be adapted to havea wide variety of other diameters. In one embodiment, the carrier 20includes fifty-four indexing holes 70. However, in other embodiments,the substrate film carrier 20 may include fewer or more indexing holes70.

[0075] Upon completion of at least a portion of the manufacturingprocess, one embodiment of the invention removes the substrate filmcarrier 20 from the substrate film 18. Upon removal of the substratefilm carrier 20, the substrate units 24 and the their corresponding dies22 are separated from each other. Thus, the substrate file carrier 20provides support during the manufacturing process.

[0076] The substrate film carrier 20 demonstrates certain advantagesover conventional handling of thin substrate films 18. One advantage isthat the substrate film carrier 20 provides enhanced rigidity to thesubstrate film during handling and die-substrate assembly. This reducesundesirable and/or unwanted bending and movement which can not onlycause damage to the die, the substrate and the die-substrate interface,but can also complicate the handling and assembly of the die andsubstrate. For example, undesirable bending of the substrate film canresult in breakage of one or more of the lead wires connecting the diesto the substrate film. The substrate film carrier 20 (FIG. 4) improvesprocessability of the die-substrate assembly 17 (FIG. 2) by providingenhanced rigidity to the substrate film 18 (FIGS. 3 and 4), and hencehelps in reducing the percentage of defective end products.

[0077] Another advantage of the substrate film carrier 20 (FIG. 4) isthat it can provide a better seal with a suction/vacuum tip, againlargely due to the enhanced rigidity it provides. In some situationsduring handling of the substrate film 18 (FIGS. 3 and 4) and/ordie-substrate assembly 17 (FIG. 2) it is desirable to use a suction tipfor holding and/or transporting the substrate film 18 and/or thedie-substrate assembly 17. The flimsiness of conventional thin substratefilms makes it difficult to use a suction tip. The substrate filmcarrier 20 (FIG. 4) allows the use of suction tips to handle thesubstrate film 18 (FIGS. 3 and 4) by providing enhanced rigidity to thesubstrate film 18. This can improve the overall speed and efficiency ofthe assembly process.

[0078] Another advantage of the substrate film carrier 20 (FIG. 4) isthat it allows for more control in selecting the thinness of thesubstrate film 18 (FIGS. 3 and 4). In general, it is desirable to have athin substrate film to reduce the weight and size of the end product.But, with some conventional substrate films the lower limit on thethickness can be dictated by the handling processability of thesubstrate film. This limitation on the thickness of the substrate filmis reduced by the substrate film carrier 20 (FIG. 4) which providesenhanced rigidity to the substrate film 18 (FIGS. 3 and 4). Moreover,the degree of rigidity and/or flexibility provided can be controlled byselection of the carrier dimensions, configuration and material choice.

[0079] While the components and techniques of the invention have beendescribed with a certain degree of particularity, it is manifest thatmany changes may be made in the specific designs, constructions andmethodology hereinabove described without departing from the spirit andscope of this disclosure. It should be understood that the invention isnot limited to the embodiments set forth herein for purposes ofexemplification, but is to be defined only by a fair reading of theappended claims, including the full range of equivalency to which eachelement thereof is entitled.

What is claimed is:
 1. A method of manufacturing an assembly comprising: combining layers of solder resist other than polyimide with a polyimide film to construct side bars; connecting said side bars to a substrate film wherein connecting said side bars comprises substantially aligning a plurality of indexing holes in said side bars with a plurality of indexing holes in said substrate film; transporting said side bars and said substrate film through a manufacturing process; and removing said side bars after at least a portion of said manufacturing process.
 2. The method of claim 1 wherein said act of connecting said side bars substantially aligns said side bars with side rails in said substrate film.
 3. The method of claim 1 further comprising the act of connecting cross bars to said substrate film.
 4. The method of claim 3 wherein said act of connecting cross bars substantially aligns said cross bars with cross rails in said substrate film.
 5. The method of claim 1 further comprising the act of interfacing said substrate film with a plurality of dies. 